Peperazinqalkyl glycolates



United States Patent 3,125,575 PIPERAZINOALKYL GLYCOLATES John H. Biel, Milwaukee, Wis, assignor to Lakeside Laboratories, Inc., Milwaukee, Wis., a corporation of Delaware N0 Drawing. Filed Mar. 14, 1960, Ser. No. 14,500 3 Claims. (til. 269-268) This invention relates to piperazine derivatives. More particularly, this invention is concerned with novel disubstituted glycolates of piperazinoalkanols and the use of such compounds to effect a psychotherapeutic effect.

This application is a continuation-in-part of my copending application Serial No. 735,356, filed May 15, 1958, now abandoned.

According to the present invention, there are provided novel compounds of the formula wherein R and R are the same or different members of the group consisting of the phenyl, halophenyl groups such as p-chlorophenyl, lower alkoxyphenyl groups such as p-methoxyphenyl, p-hydroxyphenyl, p-aminophenyl, Z-thienyl, furyl, pyridyl lower alkyl-phenyl groups such as p-methyl-phenyl, or cycloalkyl groups such as cyclo pentyl or cyclohexyl, R and R are hydrogen or a lower alkyl such as methyl, ethyl or propyl, R represents hydrogen, aryl groups such as phenyl and nuclear substituted phenyl groups such as p-aminophenyl, a halophenyl group such as p-chlorophenyl, a lower alkoxyphenyl group such as m-methoxyphenyl, and poly-lower alkoxyphenyl groups such as the m,p-dimethoxyphenyl group, hydroxyphenyl groups such as the p-hydroxyphenyl group and poly-hydroxyphenyl groups such as the o,p-dihydroxyphenyl group, aralkyl groups such as the phenyl-lower alkyl groups such as phenylmethyl, phenylethyl, phenylisopropyl and phenyl-lower alkyl groups in which the phenyl ring contains one or more nuclear substitutents such as halogens and particularly bromine or chlorine, the hydroxy group, lower alkoxy groups and the amino group, a lower alkenyl group such as the allyl group and aralkenyl groups such as the phenyl-lower alkenyl group and particularly the cinnamyl group, and Y is a straight or branched alkylene group of no more than 5 carbons, and acid addition salts and quaternary ammonium salts thereof.

These compounds, advisably in the form of nontoxic acid addition salts, exert a pronounced psychotherapeutic effect when administered to animals, and particularly humans. The compounds mildly increase motor activity, induce a mild feeling of relaxation and a relief from anxiety or restlessness. 4-phenylisopropyl-beta-piperazinoethyl benzilate is, however, a mild central nervous system stimulant. These compounds are not hypnotics and are essentially devoid of sedative activity. The compounds also have antispasmodic activity as acid addition and quaternary ammonium salts. The compounds in which R is hydrogen evidence much higher antispasrnodic activity than those where R; is a lower alkyl or a substituent of the types previously indicated. Thus, beta-piperazinoethyl benzilate HCl is a potent antispasmodic. Furthermore, the compounds of this invention do not decrease motor activity as do some of the compounds in which R is a lower alkyl. The compounds of this invention in which Y is a branched alkylene are more potent as psychotherapeutics and have lower antichlorinergic side effects than compounds in which Y is a straight chain alkylene group between the piperazino Patented Mar. 17, 1964 moiety and the glycolate moiety. Nevertheless, branchmg of Y often lowers antispasmodic activity, while the antispasmodic activity often increases when Y increases from ethylene to propylene in a straight alpha, omega chain between the ester function and the piperazine nitrogen. These compounds also form salts with penicillin and thus may be used to isolate penicillin from fermentation broths and other solutions of this antibiotic.

The compounds of this invention in which R is not hydrogen can be conveniently produced by several processes, one of which comprises reacting a lower alkyl disubstituted glycolate with a 4-substituted piperazino-alkanol to produce the desired 4-substituted piperazino-alkyl-disubstituted glycolate. This process may be reprewherein R R R R R and Y have the significance previously assigned, except that R is not hydrogen, and R is a lower alkyl group.

Some of the disubstituted glycolic acids used in the process in the form of lower alkyl esters are methyl benzilate, methyl phenylcyclohexyl glycolate, ethyl phenylcyclopentyl glycolate, methyl Z-thienyl phenyl glycolate, ethyl phenylpropyl glycolate, methyl dicyclohexyl glycolate, ethyl p-chlorophenyl furyl glycolate and methyl p-methoxyphenyl-3-pyridyl glycolate.

Some of the 4-substituted piperazinoalkanol-s which may be used in this process are 4-allylpiperazino-2-propanol, 4-cinnamylpiperazinoethanol, 4-phenylpiperazino- 3-butanol, 4-benzylpiperazino-2-butanol, 4-p-methoxyphenylethylpiperazino-4-pentanol, 4-phenylpropylpiperazino-Z-propanol, and 2-methy1-4-cinnamylpiperazino-3- butanol.

Reaction between the lower alkyl disubstituted glycolate and the 4-substituted piperazinoalkanol is conveniently effected by bringing the reactants together in a suitable inert solvent in the presence of sodium or a sodium alkoxide. Solvents such as n-heptane, toluene, xylene or an excess of the piperazino alkanol may be used for the reaction medium. The mixture is generally heated to promote the reaction with the reflux temperature being preferred. As the reaction proceeds, the lower alcohol which is formed in the reaction is distilled off. The reaction is considered completed when low boiling alcohol ceases to distill off. The product is recovered by acidifying the reaction mixture, evaporating to dryness, taking the residue up in water, adding a base such as caustic soda to the aqueous solution and extracting with an immiscible solvent. The extract may then be dried and the product recovered by distillation.

Representative of the products which are produced in this way are 4-phenylpiperazino-2-propyl benzilate, 4- benzylpiperazinoethyl benzilate, 4-allylpiperazino-3-butyl benzilate, 4-cinnamylpiperazino-Z-propyl phenylcyclohexyl glycolate, 4-phenylethylpiperazino-Z-propyl phenylcyclopentyl glycolate, 4-phenylpropylpiperazinoethyl phenyl Z-thienyl glycolate, 4-allylpiperazinopropyl phenyl 3-chlorophenyl glycolate, 4-benzylpiperazino-2-propyl furyl phenyl glycolate, 4-phenylpropylpiperazino-Z-propyl furyl Z-thienyl glycolate, and 2-methyl-4-allylpiperazino- Z-propyl benzilate.

An alternate method of producing these novel 4-substi- 3 tuted piperazino compounds wherein the glycolate substituents are both aryl comprises reacting a di-aryl substituted halo or acyloxy acetyl halide with a 4-substituted piperazinoalkanol to produce an intermediate 4-substituted piperazinoalkyl di-aryl substituted halo or acyloxy acetate which is subsequently hydrolyzed to the corresponding 4-substituted piperazinoalkyl di-aryl substituted glycolate.

This process may be represented as follows:

wherein R and R are the same or diiferent phenyl, substituted phenyl, thienyl o-r pyridyl groups, R R R and Y have the significance previously assigned, except that R; is not hydrogen, Z is a reactive halogen and advisably chlorine, and X is a reactive halogen such as chlorine or a reactive acyloxy group such as acetoxy.

Representative di-aryl substituted halo or acyloxy acetates which may be used in the process are diphenylchloroacetyl chloride, phenyl Z-thienyl chloroacetyl chloride, diphenyl acetoxy acetyl chloride and 3-pyridyl pchlorophenyl chloroacetyl chloride.

4-substituted piperazinoalkanols such as those previously named may be used in the process.

In the first step of this process the reactants may be conveniently brought together in an inert organic solvent such as benzene, toluene, isopropanol, or acetone. An acid acceptor such as triethylamine is generally included in the reaction mixture. Elevated temperatures up to the reflux temperature are generally employed to enhance the rate of reaction and maintain solubility of the reactants. The reaction product may be recovered from the mixture by conventional methods.

Some of the compounds which are produced in this way are 4-benzylpiperazino-2-propyl diphenylchloroacetate, 4-phenylpiperazino-3-butyl phenyl Z-thienyl chloroacetate, 4-phenylethylpiperazino-2-propyl phenyl 3-pyridyl chloroacetate, and 2-methyl-4-phenylpropylpiperazino-2-propyl diphenylchloroacetate.

These and other compounds within the scope of this invention are readily hydrolyzed to the corresponding 4- 'substituted piperazinoalkyl di-aryl substituted glycolate, advisably in the presence of a mineral acid and preferably hydrochloric acid.

The compounds of this invention where R; is not hydrogen can also be conveniently produced by reacting a disubstituted glycolic acid with an appropriate 4-substituted piperazinoalkyl halide. This reaction can be represented as follows:

wherein R R R R R Y and Z have the significance previously assigned except that R, is not hydrogen.

The reactants used in this process are essentially the same as those named previously except that the free giycolic acid is used plus a 4-substituted piperazinoalkyl halide instead of the corresponding alkanol. The reaction is readily effected by combining the reactants in an inert solvent such as isopropanol and heating the mix ture at an elevated temperature, such as the reflux temperature.

The piperazinoalkyl glycolates having no substituent in the 4-position of the piperazine moiety can be produced from the N-benzyl piperazinoalkyl glycolates by catalytic hydrogenation with cleavage of the N-benzyl group. This process can be represented as follows:

R3 wherein R R R R and Y have the significance previously assigned and is phenyl.

The catalytic reductive cleavage is readily effected by adding the N-benzyl piperazinoalkyl glycolate, advisably as an acid addition salt, to a solvent such as Water or a lower alcohol, adding a catalyst such as palladium, and hydrogen under pressure, as up to about p.s.i. A small amount of glacial acetic acid is generally included to promote the reaction. The hydrogenation proceeds quickly and its progress can be measured by the hydrogen uptake. When the hydrogen uptake ceases the reaction can be considered completed. After filtering the reaction mixture it can be evaporated to dryness and the product triturated with a solvent such as ether and separated by filtration.

Some of the compounds produced in this way from the corresponding 4-benzyl piperazino alkyl glycolates are beta-piperazinoethyl benzilate, gamma (2 methylpiperazino)-propyl benzil ate, beta-piperazinoethyl phenylcyclohexyl glycolate, beta-piperazinoethyl phenyl Z-thienyl glycolate and gamma-piperazinopropyl phenylcyclopentyl glycolate.

Acid addition salts are produced by contacting the compounds with a suitable acid such as formic acid, citric acid, maleic acid, sulfuric acid, hydrochloric acid, succinic acid, tartaric acid, benzoic acid or fumaric acid.

Quaternary ammonium salts are formed by contacting the compounds with a suitable alkylating agent such as: dimethyl sulfate or analkyl halide such as methyl chloride or ethyl bromide.

The active agents of this invention may be administered to animals and humans as pure compounds. It is advisable, however, to first combine one or more of the novel compounds with a suitable pharmaceutical carrier to at-- tain a more satisfactory size to dosage relationship.

Pharmaceutical carriers which are liquid or solid may Solid pharmaceutical carriers such as starch, sugar,

talc and the like may be used to form powders. The powders may be used as such for direct administration to a patient or, instead, the powders may be added to suitable foods and liquids, including water, to facilitate administration.

The powders may also be used to make tablets, or to fill gelatin capsules. Suitable lubricants like magnesium stearate, binders such as gelatin, and disintegrating agents like sodium carbonate in combination with citric acid may be used to form the tablets.

Unit dosage forms such as tablets and capsules may contain any suitable predetermined amount of one or more of the active agents as a nontoxic acid addition salt and may be administered one or more at a time at regular intervals. Such unit dosage forms, however, should generally contain a concentration of 0.1% to by weight of one or more of the active piperazines.

A typical tablet may have the composition:

Powders 1, 2 and 3 are slugged, then granulated, mixed with 4 and 5, and tableted.

Capsules may be prepared by filling No. 3 hard gelatin capsules with the following ingredients, thoroughly mixed:

Mg. (1) 4-phenylpiperazinoethyl benzilate dihydrochloride 5 (2) Lactose U.S.P 200 (3) Starch U.S.P 16 (4) Talc U.S.P 8

The oral route is preferred for administering the active agents of this invention.

The following examples are presented to illustrate specific embodiments of the invention.

EXAMPLE 1 4-Phenylpiperazinoethyl Benzilate EXAMPLE 2 Beta-(4-Benzylpiperazin0)Ethyl Benzilate Dihydrochloride This compound was prepared by the method described in Example 1. From 29.1 g. (0.13 mole) of 4-benzylpiperazinoethanol and 24.2 g. (0.10 mole) methyl benzilate, there was obtained 18.4 g. (37%) of the dihydrochloride upon acidification of the basic ester in ether, M.P. 224-225 C. dec.

Anal.-Calcd. for C27H32Cl2N2031 Cl, N, Found: Cl, 14.16; N, 5.46.

EXAMPLE 3 4-Cinnamyl Piperazinoethanol NC 1114 O H To a mixture of 39.06 g. (0.30 mole) of hydroxyethyl piperazine, 41.46 g. (0.30 mole) of freshly ground anhydrous potassium carbonate and 300 cc. of ethanol, there was added dropwise with stirring 45.8 g. (0.30 mole) of cinnamyl chloride. The mixture was refluxed with stirring for 3 hours, the inorganic salts separated by filtration and the product collected at 165 C. (0.08 mm.); yield 52.5 g. (71% Anal.Calcd. for C H N O: N, 11.37. Found: N, 11.26.

EXAMPLE 4 4-Cinnamylpiperazinoethyl Benzilate Dihydrochloride This ester was prepared by the method described in Example 1. From 28.64 g. (0.22 mole) of 4-cinnamyl- 6 piperazinoethanol and 48.4 g. (0.20 mole) of methyl benzilate, there was obtained 49.8 g. (47%) of the compound; M.P. 201202 C. Several recrystallizations from isopropyl alcohol raised the M.P. to 215 C. dec.

Anal.-Calcd. for C H Cl N O Cl, 13.41; N, 5.29. Found: Cl, 13.42; N, 5.21.

EXAMPLE 5 4-Allylpiperazinoethyl Phenyl Z-Thienyl Glycolate A mixture of 21.4 g. (0.10 mole) of 4-allylpiperazinoethyl chloride, 23.4 g. (0.10 mole) of phenyl Z-thienyl glycolic acid and 300 cc. of anhydrous isopropyl alcohol was refluxed for thirty hours. The isopropyl alcohol was removed by distillation in vacuo. The oily residue was dissolved in water and the aqueous solution extracted with ether. The aqueous layer was neutralized with potassium carbonate and extracted repeatedly with ether. The ether extracts were dried with potassium carbonate and concentrated. The basic ester was a high-boiling water-insoluble oil.

EXAMPLE 6 Beta- [4-( Z -Phenyl-2-Pr0pyl) -Piperazin0] -Ethyl Benzilate Dihydrochloride A mixture containing 11.7 g. (0.047 mole) of beta-[4- (l-phenyl-2-propyl)-piperazino]-ethano1, 10.4 g. (0.047 mole) of methyl benzilate, 250 cc. of n-heptane, 2 cc. of methanol and 0.3 g. of sodium methoxide was stirred at reflux until the distillation of methanol ceased. The warm mixture was clarified by filtration, the filtrate diluted with chloroform and washed twice with 50 cc. of water. The organic phase was dried with potassium carbonate and the solvent removed by distillation leaving 19.5 g. (90.6%) of crude basic ester. The latter was dissolved in 200 cc. of methanol and converted to the dihydrochloride salt by addition of ethereal hydrochloric acid, yield 11.1 g. (49%); M.P. 238239 C.

AnaL-Calcd. for C29H3 Cl2N2031 Cl, N, Found: Cl, 13.37; N, 5.23.

EXAMPLE 7 Gamma-(4-BenzyI-Z-Methylpipemzino) -Pr0pylbenzilate Dihydrochloride A mixture containing 24.2 g. (0.10 mole) of methyl benzilate, 24.8 g. (0.10 mole) of 4 -benzyl-2 -methylpiperazinopropanol, 0.5 g. of sodium methoxide, and 250 cc. of n-heptane was refluxed for 4 hours While 6 cc. of methanol was collected by distillation. The catalyst was removed by filtration, the filtrate washed with water, dried over potassium carbonate, and concentrated to dryness in vacuo yielding 45.3 g. (99%) of the crude basic ester. The latter was converted to the dihydrochloride salt in acetonitrile, yield 35.4 g. (67%); M.P. 207- 208 C.

Anal.Calcd. for C H Cl N O Cl, 13.34; N, 5.27. Found: Cl, 13.35; N, 5.35.

EXAMPLE 8 Beta-Piperazinoethyl Benzilate A mixture containing 25.8 g. of beta-(4-benzylpiperazino)-ethyl benzilate, 7.2 g. (0.12 mole) of glacial acetic acid, cc. of methanol and 3 g. of palladium-on-charcoal (10%) catalyst was subjected to hydrogenation at 60 p.s.i. of hydrogen. The catalyst was removed by filtration and the filtrate acidified with ethereal hydrochloric acid. The solvent was removed by distillation and the residual solid dissolved in water, neutralized with sodium bicarbonate and the oily layer extracted with tetrahydrofuran. The tetrahydrofuran extracts were dried with potassium carbonate, the solvent removed 7 8 by distillation and the residue taken up in acetone and rate the spirit of this invention, they are intended to be converted to the dihydrochloride salt by the addition of included Within the scope of the appended claims. ethereal hydrochloric acid. The solid was recrystallized What is claimed is: from a mixture of 300 cc. of isopropyl alcohol and 100 1. Beta-piperazinoethyl benzilate. cc. of methanol, yield 11.3 g. (44%), MP. 164-165" C. 2. Gamma-(Z-methylpiperazino)-propyl benzilate.

Anal.Calcd. for C H Cl N O Cl, 17.15; N, 6.77. 3. Piperazino-lower alkyl-benzilate. Found: Cl, 17.28; N, 6.47.

EXAMPLE 9 References Cited in the file of this patent UNITED STATES PATENTS Gamma-(z-Melhylpipemzilw)-Pr0l1yl 2,419,366 Northey et al. Apr. 22, 1947 Benzilale Dihydl'vchloride 2,854,379 Pancher Sept. 30, 1958 A mixture consisting of 26.6 g. (0.05 mole) of gamma- 2872374 Belief et 1959 (4 benzyl 2 methylpiperazino) propyl benzilate FOREIGN PATENTS dihydrochloride in 200 cc. of methanol was subjected to reductive cleavage at 60 p.s.i. of hydrogen with 3.5 g. of 625811 Great Bntam H July 1949 palladium-on-charcoal (10%) catalyst. The catalyst was OTHER REFERENCES removed by filtration and the SOlVCIll. by distillation. The Zaugg et aL; 10111" Amer Chem Soc, VOL '72, pages residue was recrystallized from 200 cc. of acetonitrile 3004 3007 (1950), and 300 of P PY alcohol, Yield g Goodman et al.: The Pharmaceutical Journal, vol.

M.P. 187-188" C. 181, 4952, pages 233-235, September 1958.

for zz ao z z s Laurence et al.: British Med. Jour., pages 700-702 Found: Cl, 15.84; N, 6.21. (1958).

Various changes and modifications of the invention can British Med. Jour., pages 938-939, April 19, 1958.

be made and, to the extent that such variations incorpo- Keele: The Lancet, pages 243-246, Jan. 31, 1959. 

1. BETA-PIPERAZINOETHYL BENZILATE. 